DESCRIPTION: Kaposi's sarcoma (KS) is a common AIDS-Defining illness and epidemiological features suggest the involvement of a sexually transmitted agent in the etiology of AIDS-KS. Recently, DNA sequences of a new herpesvirus provisionally named KS-associated herpesvirus (KSHV)- Human herpesvirus-8 (HHV-8) were identified in AIDS-associated and in non-AIDS KS lesions. The hypothesis derived from this is that reactivation and lytic HHV-8 replication occur under the conditions of HIV-induced reduced immune-surveillance which may precede the development of clinical AIDS-KS. Ongoing studies have identified several genes encoding immunogenic HHV-8 proteins and glycoproteins. The focus now will be to test the hypothesis by further characterizing the HHV-8 proteins associated with latent and lytic infections and to examine critically the elicited serological responses. The following three major SPECIFIC AIMS have been formulated. To define and characterize the immunogenic HHV-8 antigens associated with latent and lytic replicative cycle. To compare and evaluate the serological responses against the selected immunogenic HHV-8 lytic and latent antigens. To determine the temporal correlation between serological responses and the development of AIDS-KS and to determine whether serological responses can serve as markers for the development and progression of AIDS-KS. These studies could be significant since if HHV-8 replication precedes the development of KS then this may have important implications in the assessment of therapeutic intervention of HHV-8 infection by anti-herpes viral drugs.